KZ750 Twins .com » Suspension

Front Brake Upgrade

Biquetoast — Thu, 23 Jul 2009 02:29:50 +0000

(This post is created from content contributed by KTOF member Steell)

Want *real* stopping power from the front brake on your old KZ750 B or G model? Want double-disk performance without breaking the bank?

Fortunately, you don’t need to replace the wheel, there are provisions for the second disk on the stock wheel. But there are a few other components you will need to add or swap out.

The stock single disk is thicker and heavier than dual disk brake rotors, so you are best off to replace your one single rotor with two from a bike with a dual-disk setup (77-80 KZ1000, maybe 78-79 KZ650 but check diameter).

So you want killer brakes on that bike?

77-80 KZ1000 12″ brake rotors
83-85 GPz750 calipers
95-96 GPz1100 master cylinder
Stainless steel brake lines

It will stop you on a dime and give you change back…
I just described the brakes on my ’79 750 twin (specifically: rotors are 79 KZ1000, calipers are 83 GPz750, master cylinder is 96 GPz1100), so I know it works.

The same calipers are used on other models, same thing with the master cylinder, I just don’t remember what models/years used them.

Braided Stainless Steel Brake Lines

Biquetoast — Thu, 23 Jul 2009 02:12:43 +0000

I am of the opinion that brake line upgrades are mandatory for these old KZ’s; especially on the front. Mind you, I’ve only done that upgrade on one of my two 750′s so far, but I intend to get the other done as soon as budget allows.

Speaking of budget, I thought I’d post my parts/shopping list for the upgrades as I do them.

For my first 750, I decided to try building the stainless lines myself from components, instead of buying pre-built sets. I found a site that had a good reputation and price (mgcycle.com, a Moto-Guzzi specialist shop), and contacted them with some questions. The proprietor was a bit surprised when I told him I do not have a ‘Guzzi, but he was kind and helpful nonetheless.

Together (over a few emails), the salesperson and I came up with this list, made up of “Earl’s Brake Line Components”:

8 Copper crush washers, $0.75 each = $6
2 #600503 30 degree adjustable banjo fitting – 2 x $16.50 = $33
1 #600803 30 degree non-adjustable banjo fitting – $12.25
1 #600703 straight non-adjustable banjo fitting – $10.50
3ft #6000031 clear plastic covered braided stainless steel brake line – 3 x $7.75 per foot = 23.25

….for a grand total of $85.

Believe it or not, he ended up sending me enough excess line that I have enough to probably do the rear brake… someday. Be forewarned though, that the “Earl’s” brand is sold as individual components; meaning you cut the lines (here’s a tip, wrap it in masking tape when you go to cut with a sharp hacksaw), you assemble and crimp the ends (another tip: use some heat-shrink tubing for a professional look), and you get poked alot in the fingers by tiny little sharp stainless wires. Okay, it’s not that bad, considering the savings…

I have since found a couple other great vendors for stainless brake lines. For instance, z1Enterprises.com started selling pre-cut/crimped lines in various lengths (the kind that has a swivel that you screw together), so I used those on my KZ400 with great success, for even less money, believe it or not.

HEL Performance has special pre-built kits labeled/indicated as for the 750B models, and the Y models. Though they cost a bit more than doing it your self, it looks pretty convenient. I’d like to hear from you if you’ve used these!

Also, Spiegler sells separate kits for the front (S-KA0080, $109.95) and rear (S-KA0079, $56.95), labeled as designed for the ’76 B1 (surely designed to accommodate the hardline and the front-mounted caliper).

Remember, as always, I don’t endorse any of these vendors, I’m just passing along what I have seen out there… Anyway, I will update you all later when I get around to doing my other 750…

Tire Air Pressure

Biquetoast — Sun, 19 Jul 2009 00:16:20 +0000

(This post is contributed by KTOF member Steell)

I keep seeing posts that the correct pressure to run tires is the one printed on the sidewall. Now I have publicly stated that that info is garbage, has no basis in fact and may get someone hurt.

Here’s what Dunlop has to say:

Quote:

Follow pressure recommendations shown on the Dunlop Motorcycle Tire Application Guide. Contact Dunlop if year and model are not shown on the current guide and the owner’s manual does not list pressure settings for Dunlop tires.Keep in mind that hard cornering, passengers, heavy loads and sustained high speeds will require higher pressures (up to that indicated on the sidewall).

http://www.dunlopmotorcycle.com/infocenter_tiretips.asp?id=8#tip

And Bridgestone:

Quote:

Always keep the motorcycle manufacturer’s recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. On some motorcycles, the recommended front and rear tire pressures will be different. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well.

http://www.motorcycle-karttires.com/additionalinformation.aspx

And Pirelli:

Quote:

It is important to always inflate the tire to the correct pressure. Be sure to check cold inflation pressure frequently (i.e. once a week). Although most motorcyclists love to work on their bikes, they seldom remember to check tire pressures. Correct tire pressure, however, is critical for safe handling. Over-inflation or extreme tire pressure will impair your riding comfort and decrease the contact of the tire with the road. Under-inflation or too little air pressure will result in poor handling and the bike will be inclined to “wander.” Improper and insufficient tire pressure will also cause rapid tire wear, an increase in fuel consumption, lower top speed, and provide less control. Remember to check the inflation pressure of your tires weekly.

You will find the correct pressure in the operating manual of the motorcycle. The manufacturer’s information is the minimum values only. With luggage or with a second rider the rear tire needs an extra 0.2 bar, and for high speed riding the pressure of the front tire should also be increased by 0.2 bar.

http://www.us.pirelli.com/web/motorcycle/tyres/tyres-technology/tyres-care/Tyre_Pressure.page

And Metzeler:

Quote:

Many tyre damage result from incorrect inflation pressure. Furthermore, the inflation pressure has a big influence on the riding qualities of a motorcycle. The inflation pressure recommended by the motorcycle manufacturer can be found in the bike’s manual and is usually written on a sticker on the rear swingarm or chainguard. Set the suggested inflation pressure on cold tyres before riding. During service the tyre’s warming-up causes a pressure rise that must NOT be reduced.
Check inflation pressure once a week. Increase rear tyre pressure by 0,2 bar / 3 psi when riding with a passenger or with very heavy load. Insufficient inflation pressure causes tyre flexing and overheating that may lead to internal damage. Overinflation impairs riding comfort and stability and can result in uneven wear.

http://www.metzelermoto.com/web/products/technology/maintenance/default.page

I think that ought to be enough to make my point, and that is “Anyone telling you to always inflate your tires to the max pressure printed on the sidewall is wrong”, always follow the info in the owners manual.

For Reference: The Kawasaki Motorcycle Service Manual gives the following tire air pressures (measured when cold) for the stock tires:

’76 B1- ’79 B4 — Front: 28 psi, Rear with less than 215lbs: 32 psi, Rear with up to 365 lbs: 36 psi
’80 G1 — Front: 28 psi, Rear with less than 215lbs: 21 psi, Rear with up to 365 lbs: 28 psi
’82 M1 — Front: 25 psi, Rear with less than 215lbs: 25 psi, Rear with up to 397 lbs: 28 psi
’83 K1, S2, Y2 — US/CA Front: 25 psi, Rear with less than 215lbs: 25 psi, Rear with up to 397 lbs: 28 psi
’83 K1, S2, Y2 — EUR Front: 28 psi, Rear with less than 215lbs: 28 psi, Rear with up to 397 lbs: 32 psi